Metaphoetesis is an ecological term coined by G. E. Hutchinson, to denote a change in diet with a changing stage of the life cycle of an animal. This characteristic, exhibited by many species such as insects and fishes, is important in determining the length of a

food chain A food chain is a linear network of links in a food web, often starting with an autotroph (such as grass or algae), also called a producer, and typically ending at an apex predator (such as grizzly bears or killer whales), detritivore (such as ...

, particularly in aquatic and amphibious environments. Smaller, i.e., younger specimens belong to foodchain links below the larger -older- specimens. The concept has been described by other authors using various terms such as "life history omnivory". For instance,

lake trout The lake trout (''Salvelinus namaycush'') is a freshwater Salvelinus, char living mainly in lakes in Northern North America. Other names for it include mackinaw, namaycush, lake char (or charr), touladi, togue, laker, and grey trout. In Lake Sup ...

, ''Salvelinus namaycush'' Walbaum, 1792

Salmonidae Salmonidae (, ) is a family (biology), family of ray-finned fish, the only extant member of the suborder Salmonoidei, consisting of 11 extant genera and over 200 species collectively known as "salmonids" or "salmonoids". The family includes salmo ...

, a Holoarctic freshwater fish species, exhibit different growth patterns within a single lake at a given time and among ensembles of similar lake types. These growth patterns are related to the species' food habits, and have consequences in growth rate, age at maturity, etc. Small, fast-growing, precocious adult trouts are

planktivores A planktivore is an aquatic organism that feeds on planktonic food, including zooplankton and phytoplankton. Planktivorous organisms encompass a range of some of the planet's smallest to largest multicellular animals in both the present day and i ...

, and inhabit lakes that are devoid of fish prey, while large, slow-growing, delayed maturation trouts are

piscivores A piscivore () is a carnivorous animal that primarily eats fish. Fish were the diet of early tetrapod evolution (via water-bound amphibians during the Devonian period); insectivory came next; then in time, the more terrestrially adapted repti ...

and inhabit lakes where fish prey is abundant (Kerr, 1979). A more recent article, not related to metaphoetesis per se, associates the reduction of lake trout populations in North American and European lakes to

acid rain Acid rain is rain or any other form of Precipitation (meteorology), precipitation that is unusually acidic, meaning that it has elevated levels of hydrogen ions (low pH). Most water, including drinking water, has a neutral pH that exists b ...

which wiped out the populations of ''

Mysis ''Mysis'' is a genus of mysid crustaceans in the family Mysidae, distributed mainly in the coastal zone of the Arctic and high boreal seas. Several species also inhabit northern freshwater lakes and the brackish Caspian Sea. Fifteen species are ...

'' species (''

Mysis relicta ''Mysis relicta'' is a shrimp-like crustacean in the Mysida order, native to lakes of Northern Europe and to the brackish Baltic Sea. Appearance Mysis is a small, transparent shrimp-like crustacean, of less than 2.5 cm length. It has two p ...

'' and '' Mysis salemaai'' in Europe and ''

Mysis diluviana ''Mysis'' is a genus of mysid crustaceans in the family Mysidae, distributed mainly in the coastal zone of the Arctic and high boreal seas. Several species also inhabit northern freshwater lakes and the brackish Caspian Sea. Fifteen species are ...

'' in North America). These are rather large (ca. 2.5 cm long)

benthopelagic The demersal zone is the part of the sea or ocean (or deep lake) consisting of the part of the water column near to (and significantly affected by) the seabed and the benthos. The demersal zone is just above the benthic zone and forms a layer of ...

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

s that thrive in

oligotrophic An oligotroph is an organism that can live in an environment that offers very low levels of nutrients. They may be contrasted with copiotrophs, which prefer nutritionally rich environments. Oligotrophs are characterized by slow growth, low rates o ...

, well-oxygenated waters, precisely the habitat of lake trout. Lesley Evans Ogden, Acid Rain: Researchers Addressing Its Lingering Effects, BioScience, Volume 68, Issue 11, November 2018, Page 928, https://doi.org/10.1093/biosci/biy113 No reference is made to whether these trout populations are intermediate in size and maturation age between the planktivore and the piscivore.

References

{{ecology-stub Ecological processes Population ecology